Pile composite fabric with foamed adhesive

ABSTRACT

A composite fabric in the form of a carpet tile including a fibrous material and a substrate material formed of deaerated thermo-plastics material having a density in the range 4-10 lbs./sq. yard. The thermo-plastics material forms an exposed surface of the carpet tile and the fibrous material forms a layer embedded in the deaerated thermo-plastics material remote from the exposed surface. A lightweight layer of pile-forming material having a density in the range 6-8 oz/sq. yard is bonded to the substrate material at the surface thereof remote from the exposed surface and a bonding agent, in the form of a layer of a foamed plastics material in a gelled state, secures the layer of pile-forming material to the substrate material.

This is a division of application Ser. No. 439,931, filed Feb. 5, 1974,now U.S. Pat. No. 3,953,269.

This invention relates to composite fabrics and to a method andapparatus for manufacturing a said fabric.

Composite fabrics which are presently available consist of two or morelayers of different materials or fabrics joined together either by astitching technique or by bonding utilising adhesives, and in the lattercategory are to be found modern floor coverings such as carpet tiles andmodern wall coverings.

With the introduction of lightweight fabrics having weight in the range4-12 oz./sq. yards it has become desirable to support these fabrics on asubstrate or base. Melded fabrics, which are of light weight areparticularly difficult to bond to a backing layer with conventionaladhesives because the adhesive tends to penetrate through the meldedfabric and soil the surface of the fabric. Consequently it is an objectof the present invention to provide an improved form of composite fabricand a method of bonding a lightweight fabric to a backing layer orsubstrate in order to produce a composite fabric of commercially viablequality. Another object of the present invention is to provide apparatuscapable of carrying out the aforesaid method.

It is also an object of the present invention to provide a method andapparatus for producing a composite fabric from materials ofsubstantially different weights per unit area.

According to the present invention there is provided a composite fabriccomprising a layer of lightweight material bonded to a substratematerial by an interlayer of foamed thermo-plastics material.

Preferably the substrate material comprises deaerated thermo-plasticsmaterial which may incorporate a layer of fibrous material such asglass-fibre scrim.

Further according to the present invention there is provided a method ofmanufacturing a composite fabric comprising coating one surface of a webof lightweight material with a layer of foamed thermo-plastics material,applying the coated surface of the lightweight material to a substratematerial, heating the foamed thermo-plastics material to effectgellation thereof in order to form a composite fabric.

Further according to the present invention there is provided apparatusfor carrying out the method of the preceding paragraph, said apparatuscomprising means for supplying lightweight material from a supplystation to a device for applying foamed thermo-plastics material to asurface of said lightweight material, means for supplying a substratematerial and means for applying said substrate material under heat tothe coated surface of the lightweight material.

Different aspects of the present invention will now be described by wayof example with reference to the accompanying drawings which illustratespecific exemplary embodiments and in which:

FIG. 1 is a diagrammatic cross-sectional view of a composite fabric inthe form of carpeting.

FIG. 2 is a diagrammatic view of apparatus for manufacturing the fabricof FIG. 1;

FIG. 3 illustrates a modified version of a detail of FIG. 2;

FIGS. 4a and 4b together form a view similar to FIG. 2 but showing theapparatus in greater detail;

FIGS. 5a and 5b together form a plan view of the apparatus of FIG. 4;and

FIGS. 6 and 7 illustrate different details of the apparatus of FIG. 4.

As is illustrated in FIG. 1 the fabric 10 comprises a substrate 11 whichis in the form of a gelled layer of heavyweight P.V.C. 12 (of the order4-10 lbs./sq.yd.) containing a glass-fibre scrim or mat 12A. Thelightweight material 13, in this instance, is a melded fabric having afibre weight of the order of 6-8 oz./sq. yd. and it is bonded to thesubstrate 11 by means of a layer 14 of foamed thermo-plastics materialin a gelled state. Although the scrim 12A has been illustrated ascentrally disposed within the thickness of the substrate 11 this ismerely for ease of illustration. The scrim 12A may be at any depthwithin the P.V.C. layer 12 and, conveniently, is arranged to lie justbelow the upper surface of the P.V.C. layer 12; that is, closelyadjacent the interface between the P.V.C. layer 12 and the layer 14.

The apparatus shown in FIG. 2 comprises an endless conveyor belt 20having a non-stick surface and the upper run of the belt 20 passes underfirst means 21 where it receives the material to form the substrate 11of the composite fabric, and subsequently the belt passes a second means22 where it receives the layers 13 and 14 of the fabric. The layers 13and 14 are applied simultaneously to the substrate 11 within a heatingzone 23 and subsequent movement of the belt 20 carries the materialsthereon through a primary cooling zone 24 at the output of which theformed composite fabric is stripped from the belt by means 25 and ispassed through a secondary cooling zone 26 to a tile cutting device 27.

The first means 21 comprises an applicator 50 which incorporates adoctor blade and which is arranged over a belt-supporting roller tospread deaerated thermo-plastics material onto the belt 20, drivennip-rollers 51 arranged to pull glass-fibre scrim from one of two supplyrolls 52 and to lay the scrim onto the thermo-plastics material, and asecond applicator 53, the use of which is optional, to spread a layer ofdeaerated thermo-plastics material on top of the glass fibre scrim so asto form the substrate 11.

The heating zone 23 is formed by a plurality of flat heating plates 54,in this case seven, each having a machined upper surface andincorporating an electric resistive heating element and these plates arearranged to be adjustable for level so as to provide sufficient heatwhereby by the time the substrate 11 reaches the last heating plate 54'the thermo-plastic content of the substrate is in a gelled condition. Atthis point the second means 22 applies to the substrate 11 the layers 13and 14.

The primary cooling zone 24 includes six individually adjustablewater-cooled plates having a machined upper surface in order to maintaingood contact with the belt 20. The water supply to the plates is from arefrigeration unit (not shown).

The second means 22 comprises driven nip rollers 55 which feed a supplyof the lightweight material forming the layer 13 from one of two supplyrolls 56, a pair of heating elements 57 over which the material is fedin order to drive off excess moisture therefrom, an applicator 58 forapplying foamed thermo-plastics material to the material and a drivenlamination roller 59 which co-operates with the last heating plate 54'to apply the material forming the layers 13 and 14. The applicator 58comprises a trough 58A containing aerated thermo-plastics material adriven lick roller 58B which co-operates with the material forming thelayer 13 and a doctor blade 58C which co-operates with the roller 58B toensure a uniform foam coverage thereof.

FIG. 3 shows a modification of the applicator of FIG. 2 and comprises atrough 60 containing a doctor blade, the lightweight material being fedthrough the trough 60 to receive its coating of thermo-plastics foam.

The apparatus of FIG. 2 is shown in greater detail in FIGS. 4a, 4b, 5aand 5b from which it can be seen that the secondary cooling zone 26comprises a chamber 70 through which refrigerated air supplied from arefrigerating unit (not shown) is passed and the composite material isconveyed on a slatted conveyor 71 to achieve maximum cooling of thesubstrate 11. Conveniently the conveyor 71 runs slightly faster thandoes the belt 20, by say 5%. A maximum belt speed of 25ft./min. isenvisaged.

The belt 20, which may be made of P.T.F.E. coated glass fibre, isoperated from a main drive unit 72, through a main drive roller 73,tension being maintained in the belt by a weighted tension roller 74from which a tachometer output is taken in order to synchronise thespeed of a secondary drive unit 75. The unit 75 drives the laminatingroller 59, the nip rollers 55, the lick roller 58B and the nip rollers51.

In order to maintain the location of the upper run of the belt 20centralised with respect to the longitudinal centre line of the heatingzone 23 and the primary cooling zone 24 the end of the belt 20 adjacentthe first means 21 is carried by a pair of rollers 76 which are mountedon a yoke 77 which in turn is mounted to permit limited pivotal movementrelative to a fixed support 68. The pivotal movement of the yoke 77 iseffected by a hydraulic ram (not shown) which is controlled by apneumatically-operated belt edge sensor 78. The sensor 78, see FIG. 6,is supplied with air at a carefully maintained pressure and operates acontrol system to maintain the edge of the belt continuouslyintercepting an air jet the exact location of which is selectivelyadjustable by means of a vernier adjustment screw 79.

In order to maintain the location of the fibre-glass scrim centralisedwith respect to the upper run of the belt 20 the lay-on unit whichcomprises the nip rollers 51 and possibly also the supply rolls 52, ismounted on a wheeled carrier 80 confined to move on a gantry extendingtransversely of the belt 20. The carrier 80 is positioned by a hydraulicram 81 which in turn is controlled by a pneumatically-operated belt-edgesensor 82 similar to the sensor 78, the sensor 82 being mounted, withvernier adjustment, on a fixed support and arranged to sense theposition of the edge of the fibre-glass scrim.

In a similar manner the lay-on unit for the lightweight material to formthe layer 13 and which comprises the nip rollers 55, the heatingelements 57 and the applicator 58, is mounted on a wheeled carrier 84confined to move on a gantry extending transversely of the belt 20. Thecarrier 84 is positioned by a hydraulic ram 85 which in turn is operatedby a pair of pneumatically-operated sensors 86, 87 each similar to thesensor 78. The sensor 86 is arranged to sense the edge of thelightweight material and is mounted with vernier adjustment on a slide88 (FIG. 7) which is positioned by a hydraulic cylinder 89 in responseto the output from the sensor 87 which is arranged to sense the edge ofthe belt 20 adjacent the laminating roller 59.

To enable the described apparatus to handle different weights ofmaterials the drive units 72, 75 are each infinitely variable in speed,the laminating roller 59 is movable within limits longitudinally of thebelt 20, the means 21 incorporates a vacuum cleaning head 90 and asimilar head 91 is provided in the means 22, and the underside of thebelt 20 is cleaned by a brush 92.

By virtue of the heat applied to the constituent layers of the compositefabric 10 within the heating zone 23 the thermo-plastic content of thefabric 10 is gelled and after traversing the primary and secondarycooling zones the fabric is cut into lengths as desired. In order toobtain a dimensionally stable product which may be die cut to formcarpet tiles the substrate 11 is formed on a substantially flat surfaceand the heating and primary cooling zones 23, 24 are each formed from aplurality of substantially flat plates. This permits the substrate 11 tobe substantially stress-free and substantially dimensionally stable andin order to further improve this stability the fibre-glass scrim 12A isincorporated within the substrate 11.

The lightweight material 13 may be non-woven, needled, bonded or meldedor open-weaved in construction, all of which are porous and consequentlywhen `wetted` from one side tend to become soiled on the other side.This problem has been overcome by utilising a bonding agent in the formof foamed thermo-plastics material which tends to sit on top of thematerial 13 without substantial penetration.

A foamed thermo-plastics material of the following formulation givesgood results:

    ______________________________________                                        Materials             Parts by Weight                                         ______________________________________                                        P.V.C. Homo-Polymer   56                                                      P.V.C. Co-Polymer     24                                                      P.V.C. Granular Homo-Polymer                                                                        30                                                      Plasticiser           80                                                      Calcium Carbonate     56                                                      Stabiliser            2                                                       Viscosity Depressant  2                                                       Foaming Agent         4                                                       Carbon Black Paste    1                                                       ______________________________________                                    

In order to minimise shrinkage of the material 13 during the bondingprocess the heat applied thereto must be of limited duration andintensity. Conveniently this is achieved by locating the laminatingroller 59 over the plate 54' and a heating period of about 10 seconds issufficient to obtain a good bond between the material 13 and thesubstrate 11. The heat transfer time may also be minimised if the foamedmaterial is black in colour. Conveniently the material 14 has a densityin the range 0.35 to 0.65 gm/cc. at temperatures of less than 35° C andgells at a temperature of about 140° C so that it may be used as abovedescribed with P.V.C. material forming the substrate and which gells ata temperature within the range 146° - 154° C.

Although the material 13 has been described hereinabove as beinglightweight the apparatus of the embodiments may successfully beutilised with any combination of weights of materials. Thus, thesubstrate 11, may or may not include a fibre-glass scrim and may or maynot be in the form of a conventional fabric. Likewise the material 13may be in the form of pile for forming carpeting or other householdplenishings usually having a density in the range 12-15 oz./sq. yd.

What is claimed is:
 1. A composite fabric comprising:a substratematerial formed of deaerated thermo-plastics material and fibrousmaterial, the thermo-plastics material forming an exposed surface of thecomposite fabric, the fibrous material forming a layer embedded in saiddeaerated thermo-plastics material remote from said exposed surface, alayer of porous lightweight pile material being of lesser density thanthe deaerated thermo-plastics material and bonded to the substratematerial at the surface thereof remote from said exposed surface, and abonding agent in the form of a layer of foamed plastics materialsecuring said layer of porous, lightweight pile material to saidsubstrate material without substantial penetration of said pilematerial.
 2. A composite fabric in the form of a carpet tilecomprising:a substrate material formed of deaerated thermo-plasticsmaterial having a density in the range 4-10 lbs/sq. yard and fibrousmaterial, the thermo-plastics material forming an exposed surface of thecarpet tile, the fibrous material forming a layer embedded in saiddeaerated thermo-plastics material remote from said exposed surface, alightweight layer of porous pile-forming material having a density inthe range 6-8 oz/sq. yard bonded to the substrate material at thesurface thereof remote from said exposed surface, and a bonding agent inthe form of a layer of a foamed plastics material in a gelled statesecuring said layer of porous pile-forming material to said substratematerial without substantial penetration of said pile-forming material.3. A composite fabric as claimed in claim 2, wherein said fibrousmaterial is in the form of a scrim made of fiberglass.
 4. A compositefabric as claimed in claim 2, wherein said thermo-plastics materialcomprises P.V.C.
 5. A composite fabric as claimed in claim 4, whereinsaid foamed plastics material comprises P.V.C.